1. Field of the Invention
The invention is an optical correlator system having reflective optical components positioned along an asymmetrically folded optical axis or path between an electromagnetic radiation beam generator, which can be a laser that generates a beam of coherent light, and an output light detector for recognition of information processed along the optical path by active ones of the reflective optical components.
2. Description of the Related Art
Optical correlators can perform complex pattern recognition more rapidly than known digital techniques. Optical correlators are capable of processing large amounts of data in a data stream that can be useful in the detection, extraction and classification of desired information included in the data. Although known optical systems can perform extremely high speed, two-dimensional pattern recognition, their development has been hindered by the lack of suitable optical components; particularly at the input plane and at the spatial filter plane. However, the recent development of magneto-optic display assemblies (for example, see William E. Ross' U.S. Pat. No. 4,550,983, which is assigned to the same assignee) now provide a two-dimensional array of electronically programmable light shutters or valves that can be used to enter information into optical correlators at very high rates, e.g., at this time about 2000 frames per second. Such optical correlators can operate in, or nearly at, real-time. [See Mills and Ross, "Dynamic Magneto-optic Correlator: Real-time Operation", Society of Photo-Optical Instrumentation Engineers (SPIE) Acoustic-Optic, Electro-Optic and Magneto-Optic Devices and Applications (1987) vol. 753, pp 54-63.]
U.S. Pat. No. 5,148,496 by Robert H. Anderson, similarly assigned, teaches a discoid optical correlator system having reflective optical components positioned along a symmetrically folded optical axis or path between a source of light and an output light detector.
The discoid optical correlator system of Patent '496 has the folded optical path developed within a special disk. By definition, the disk is circular in shape and its perimeter or rim is regular. As a circle, its diameter D is the root in any determination of a folded optical path which is composed of one or more path segments (D, 2D,..nD). Therefore, each segment has a length determined by D, and each is of equal length as taught by this Patent. Also, the total length of the optical path and the number of its path segments in a folded configuration within the discoid is limited by its regular circumference or perimeter. This further determines the number of optical correlator components that can be positioned along the optical path.
The '496 Patent also teaches that the optical components are either active or passive. Its active optical components, excluding the laser diode and the charge coupled detector (CCD) array, are the input spatial light modulator (SLM) chip and the filter SLM chip. The passive components are the several concave and plane mirrors. These active and passive components are positioned along the symmetrical optical path between the laser diode and the CCD detector array in a sequence dictated by the disk diameter D which interposes passive optical components to link the active components. In the '496 Patent, the linear optical correlator path which is symmetrically folded within the discoid structure does not sequentially alternate and interpose the passive optical components in a desired active-passive-active-passive arrangement between a source of electromagnetic radiation and a detector array.